1. Field of the Invention
The present invention relates to the removal of pollutants from air by direct flame incineration, and to an apparatus and method for accomplishing the same.
2. Description of the Prior Art
In the operation of various types of processing plants, where a polluted air effluent is discharged into the atmosphere, a common method for removal of such pollutants is direct flame incineration. A typical example of such air contaminating effluent is that which is discharged from a conventional coffee roasting oven. The effluent from a coffee roaster is air carrying particulate matter and a variety of gaseous organic compounds, such as esters, aldehydes, ketones, and acids. With effective direct flame incineration, these organic pollutants can be oxidized to form carbon dioxide and water, which with the effluent air can then be discharged harmlessly into the atmosphere.
The prior art attempts at direct flame incineration have encountered various problems. In some instances, the heat transmitted from the incinerating apparatus to adjacent structure has been sufficiently high to create a fire hazard. Often this requires quite bulky installations of refractory material which adds considerably to the weight of the apparatus. Another problem with many of the prior art incinerating devices is that the apparatus is of sufficient complexity that the cost of initial installation and also the cost of maintenance are undesirably high. Yet another problem with some prior art devices is the unnecessarily high consumption of fuel needed to obtain proper incineration; also most such prior art devices are limited in the kind of fuel required, in that natural gas must be used to get adequate combustion.
One prior art incinerating device is shown in U.S. Pat. No. 3,549,333, Tabak. In the Tabak patent, there is shown an incinerating apparatus having a burner which utilizes a portion of the effluent to be incinerated and mixes this with a fuel to provide initial combustion. Downstream of the burner, there is a second flow of effluent which mixes with the flame from the burner. To provide sufficient time, temperature and turbulence for adequate combustion, the Tabak device utilizes a rather elongate combustion section downstream from the end of the burner so that there can be substantially complete oxidation of the effluent.
Examples of several other prior art combustion devices are disclosed in the following U.S. patents: Ruff et al, U.S. Pat. No. 3,090,675; Leistritz, U.S. Pat. No. 3,254,963; Wolfersperger, U.S. Pat. No. 3,276,693; Beasley, U.S. Pat. No. 3,560,165; and Reed, U.S. Pat. No. 3,368,605.
In view of the prior art, it is an object of the present invention to provide a direct flame incinerating apparatus and method, adapted for use in incinerating an effluent, such as that discharged from a coffee roasting oven, but not limited thereto, wherein there is a desirable balance of such features as high operating efficiency, substantially complete pollutant oxidation, structural simplicity and compactness, and ease of operation and maintenance.